Vehicle towed trailers have a rigid axle on which the wheels are rotatably supported. The axle is disposed beneath the load floor of the trailer. The body of the trailer is supported above the axle by leaf springs. Two or more shock absorbers are employed between the axle and the trailer floor to dampen the road vibrations. Depending on the load to be transported on the trailer, the wheel will have a rolling radius between twelve and twenty-two inches. This will position the trailer floor approximately eighteen to thirty inches above the ground.
The trailer generally has a tiltable bed portion which will permit the rear of the trailer to be positioned near or in abutment with the ground. Components, such as snow mobiles and all terrain vehicles, which are to be loaded are then driven or winched onto the tilted trailer bed. Care must be taken by the operator during loading to ensure that the trailer bed is not returned to the flat position too rapidly. Also the tilting structure adds cost and manufacturing complexity to the trailer as well as a hazard if the locking mechanism of the tilt structure is not properly employed.
When the trailer does not have a tiltable body portion, additional ramps are utilized to assist in loading the components onto the trailer. The ramps must be stored on the trailer during towing so that they will be available for unloading the components. Alternatively, the trailer can be detached from the towing vehicle and tilted at the rear axle to facilitate loading. However, the angle at which the trailer must be tilted is quite large which makes the loading of heavy items very difficult and hazardous.
Low load floor trailers have been proposed for use with semi-trailer. These trailers have multiple wheel on each side of the which are independently suspended and the trailer does not lend itself to tilting. The suspension systems of these trailers do not have a cross tie member such that provisions must be made at each wheel for absorbing transverse loading of the wheel. One prior art suspension system employs spaced guide pads between which a portion of the trailing arm is disposed for each wheel. Another of these structures incorporates an arm which is pivotally mounted between the trailing arm of the wheel and a central point on the frame. These suspension systems do not allow trailer loading without the use of loading ramps or having the trailer parked at a loading dock.